Update avrdude to upstream release 6.3

Signed-off-by: Paul Wassi <p.wassi@gmx.at>

- Build with -D_GNU_SOURCE to expose "loff_t" required for libelf.h
 - Include sys/types.h before usb.h to provide missing u_int*_t types

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

Signed-off-by: Ted Hess <thess@kitschensync.net>